Centrifugal separator



NOV- 7, 1939 c. R. A. M. BJRNSTJERNA 2,178,547

CENTRIFUGAL SEPARATOR I Filed June 9, 1937 2 Sheets-Sheet l m .C W 4 w n w.. ...Eux MN mm QR wmw m I ay vw\\\\\,\ .w a m wm QN I l m. M M E... ff Q ,v cm1 N nm 0V s w xm M W w i N0V- 7 1939. c. R. A. M. BJRNSTJERNA 2,178,547

CENTRIFUGAL SEPARATOR Filed June 9, 1957 2 Sheets-Sheet 2 Patented Nov. 7, 1939 PATENT. OFFICE v l CENTRIFUGAL SEPARATOR Curt Roger Adolf Magnus Bjrnstjerna, Djursholm, Sweden, assigner to The De Laval Separator Company, New York, N. Y., a corporation of New Jersey Application June 9, 1937, Serial No. 147,244 In Sweden June 26, 1936 i 3 claims. (o1. 223-20)v In separating treatments special dimculties'are experienced with regard to the discharge of the heavier component when this is sludge, owing to its high viscosity.

` To overcome these diiculties several constructions have been suggested, which are based on intermittent opening in the axial direction of the peripheral ywall of the sludge space when this has become liilled. All of these constructions have the common characteristic that at least one phase hereof (the opening or the closing of the slit in the bowl wall) is effected hydraulically. Further they have the common feature that the movable part or the slide is so placed relative to the other members of the bowl that tightenings must be used between the sludge space of the bowl and the hydraulic pressure-chamber. The disadvantages 'of this are evident: as a completely tight joint can never be obtained with packings of this type, rst, regulating liquid penetrates into the sludge space, a contamination of the sludge and the separated liquid thereby also taking place, and secondly, sludge may penetrate into the pressure chamber and contaminate the regulating liquid; lthis sludge iinally causes objectionable wear of the tightening mechanism and the guiding surfaces of the slide.

The difficulties referred to above in a separator are eliminated by the means shown inthe accompanying drawings, in which:

Fig. 1 lis a. sectional View of a bowl formed in accordance with the invention; and

Figs. 2, 3 and 4 are similar views of modified forms of bowls.

As shown by Fig. l the unseparated liquid flows through the tube I into the chamber 2 provided in the nave 3 of the bowl, whence it proceeds through the openings 4 and the channels 5 in the distributor S into the sludge space 1, which is formed by the xed hood 8 and the movable slide 9. The heavier sludge particles are immediately separated here. A nish separation is then ef" fected in the spaces I6 between the discs II, the purified liquid then leaving the bowl through the F holes i2 and the sludge flowing into the sludge space l. Into the chamber I4 formed between the slide 9, which is movable in axial direction on the nave 3, and the member I3 which is xed to the said nave, regulating liquid is supplied through the channels I5 and I6, the said chamber i4 thereby being lled. At the periphery of the slide 9 openings l'I are provided for the discharge of the liquid, the dimensions of these openings being such that less liquid discharges therethrough than is being supplied, They are vprovided for the purpose of emptying the chamber I4 when the supply through I6 ceases. Owing to theV centrifugal force the axial pressure of the liquid contained in I4 becomes greater than that in the sludge space 'I and also directed in the 5 opposite direction. Because of this the slide S is'pressed up against the hood 8 and makes a tight joint with the tightening device I8 in the hood, so that the slit I9 between the slide and the hood is shut. Level outlets are also pro- 1,0 vided which insure that the chamber I4 can never become filled further towards the center than to the said outletsf.

When the chamber I has become filled with sludge this must be discharged which may benl-.5 effected in .several ways. According to Fig. I a

member 2l visxed to the slide 9 and between the said member and the member I 3 a chamber 22 vis formed. `This is filled with liquid through a tube 23 at the same time as the supply to the 20 chamber I4 is interrupted. The chamber I4 is emptied through the channels I1 and the slide 9 is pressed downwards by the liquid in the chamber 22, thereby opening the slit I9 and the sludge ows out. During this period the supply through 25 tube I should suitably be interrupted. The tube 23 is now closed, the liquid contained in chamber 22 is drained thru the openings 24, thev chamber I4 is lled again and the slide moves upwards.

In order to prevent leakage from I4 tov 22, pack- .30 ings 25 and 26 having an outlet 21, are provided.

The lemptying may also be4 eiected according to Fig. 2. Between the slide 9 and the nave 3 a spring 28 is provided which tends to press the slide 9 downwards. When the chamber I4 has 35 been emptied of liquid by closing the supply I5, the axial upwardly vdirected pressure on the slide disappears, and the spring presses it down. Both the member 2l and the spring 28 may be dispensed with, the liquid pressure present in the sludge chamber thereby effecting the opening.

Fig. 3 shows a modification of Fig. 1. The drain channels I 'I are not provided. When the chamber I4 is filled, the excess liquid flows out through the channel 29a. The dimensions of 45 this channel are such that it can only take the normal ow through I5, which exists during the period when the sludge space is closed. If now the flow through the inlet I5 is increased, the liquid is forced to flow through the channel 29 50 into the chamber 22 which is thus filled. As the pressure in this chamber is greater than in I4, the slide 9 is forced down. The liquid contained in I4 thereby partly discharges through the channel 20a and partly flows into the chamber 22 55 through the channel 29. The ligure shows that the separating chamber and the pressure chamber at the periphery are entirely separated. At the nave the conditions are the same as the guiding surface of the slide is here positioned inside the surface of the liquid layer.

There may be a possibility that the sludge and the regulating liquid are mixed'the one with the other after they have left the bowl. This would take place through leakages between the collecting vessels for the different constituents. There is in fact a risk of such leakages owing to the powerful air currents which are produced by the fan action of the bowl which is considerable at the radius it has in the present case. These air currents may however be reduced by known arrangements, for instance by providing wings on the covers. Another method is to let the edge of the covers approach the rotation center as much as possible.

According to Fig. 4 the latter alternative has been used. The operation of the separator is in principle the same as above. As shown in the figure, however, the bowl spindle, the nave 3a andthe distributor 6a are integral. The slide 9a still forms the bottom of the sludge chamber 1a, but the pressure chambers Ma and 22a are located in a chamber below the bowl and separated therefrom by the cover 30 which extends towards the center, the cover at the same time also forming a bearing 3l for the revolving pants of the separator. In order to enable construction the slide 9a has been provided with an extra part 29a. With the small diameter of the bearing 3| there are no diliculties in preventing air currents from passing through. The opening and closing part works in another chamber which is separated from the separating part of the bowl.

What I claim and desire to protect by Letters Patent is:

1. A centrifugal separator including a bowl comprising an axially fixed. wall member and an axially movable wall member having peripheral engaging portions and shaped to provide a separating chamber having a sludge space adjacent the peripheral engaging portions and arranged to be closed by their engagement, and means for axially moving the movable wallmember to effect opening and closing of the sludge space, said means comprising an annular skirt extendlng axially from the side of the movable member exteriorly of the bowl, a fixed wall member engaging the annular skirt and forming therewith a pressure chamber, and means for introducing fluid into said pressure chamber to control movement of the movable wall member.

2. A centrifugal separator including a bowl having a separated liquid outlet relatively near its axis of rotation and comprising an axially iixed wall member and an axially movable Wall member having peripheral engaging portions and shaped to provide a separating chamber having a sludge space adjacent the peripheral engaging portions and arranged to be closed by their engagement, and means for axially moving the movable wall member to eect opening and closing of the sludge space, said means comprising an annular skirt extending axially from the side of the movable member exteriorly of the bowl, a iixed wall member engaging the annular skirt and forming therewith a pressure chamber, and means for introducing fluid into said pressure chamber to control movement of the movable wall member, said movable wall member being imperforate from a radius less than that of said liquid outlet to a point at the periphery thereof a substantial axial distance from the engagement of said peripheral engaging portions.

3. A centrifugal separator including a bowl having a separated liquid outlet relatively near its axis of rotation and comprising an axially xed wall member and an axially movable wall member having peripheral engaging portions and shaped to provide a separating chamber having a sludge space adjacent the peripheral engaging portions and arranged to be closed by their engagement, and means for axially moving the movable wall member to eiect opening and closing of the sludge space, said means comprising a cylindrical surface extending axially from the side of the movable member exteriorly of the bowl, a fixed wall member engaging said cylindrical surface and forming therewith apressure chamber, and means for introducing fluid into said pressure chamber to control movement of the movable wall member, said movable wall member being imperforate from a radius less than that of said liquid outlet to a point at the periphery thereof a substantial axial distance from the engagement of said peripheral engaging pOltions.

CURT ROGER ADOLF MAGNUS BJRNSTJERNA. 

